Jul 19, 2017

One of the planet’s largest shark species is rarely encountered because it roams the shadowy depths between 600 and 3,000-plus feet. The sixgill shark, which can measure to about 18 feet, is therefore mysterious and alluring.

That’s why scientists aboard the EV Nautilus were excited to document the presence of two sixgill sharks last week while using an ROV to probe the depths around California’s Channel Islands.

Both encounters, although brief, were caught on video as the sharks entered the ROV’s lights. (Videos accompany this post.)

“That could be a sixgill shark,” one of the crew says in the first minute-long clip, posted to Twitter on July 11.

Moments later the robust shark is fully in view, prompting a scientist to marvel, “Wow… check this out,” as the shark swims slowly through artificial light.

The next day a different sixgill shark provided a longer and closer look, inspiring this remark, “He’s giving us a little show.”

During the second encounter, a crab briefly stole the spotlight as it crawled across the ocean floor, and into the ROV’s lights, toting another crab in its claws. (In the YouTube video at 1:07.)

“Is that a taxicrab?” a scientist wondered aloud, prompting another scientist to answer, “It’s an Uber crab.”

The researchers did not identify the crab species, but there was no mistaking the shark species.

Sixgill sharks are so-named because they possess six gill slits on each side of their heads, versus five for most other shark species.

The peculiar-looking sharks, which prey largely on seals, fish, squid, crabs and smaller sharks, are most closely related to fossil species dating back 200 million years to the Triassic period of the Mesozoic Era.